The present invention relates to a magnetic recording head having a function for inducing magnetization reversal by applying a high-frequency magnetic field to a magnetic recording medium, and to a magnetic recording and reproduction device.
In order to achieve higher recording densities for a magnetic recording head mounted in a hard disk device, it is necessary to narrow the width and pitch of write tracks, and thus correspondingly narrow the magnetically recorded bits encoded in each write track. One challenge in narrowing the width and pitch of write tracks is decreasing a surface area of a main pole of the magnetic recording head at an air bearing surface of the recording media. Specifically, as the main pole becomes smaller, the recording field becomes smaller as well, limiting the effectiveness of the magnetic recording head, and at some degree of miniaturization, with prior technology it is no longer possible to achieve a recording field sufficient to effectively record magnetic information into the media with such a conventional recording head. One prior technology that has been proposed to address this issue is a high-frequency magnetic field-assisted recording method (MAMR: microwave-assisted magnetic recording), in which a spin torque oscillator is formed on the main pole, and a high-frequency magnetic field is applied to the recording medium in order to reduce the coercive force of the medium, and in this state, a recording field is applied to the medium in order to record data. In addition, a method has also been proposed in which the recording portion of the main pole is inclined with respect to the substrate surface, a spin torque oscillator is disposed on the inclined surface, and the head field intensity is effectively increased.
One challenge with spin torque oscillators is that it is difficult to manufacture them to have a high spin torque efficiency. High spin torque efficiency during MAMR improves the performance of the spin torque oscillator. One factor that can negatively affect spin torque efficiency is defects in the crystal orientation of the materials forming the spin torque oscillator. Point and long range defects in the crystal growth of the spin torque oscillator can cause the spin polarization and/or perpendicular anisotropy (Hk) in the spin polarized layer (SPL) and/or field generating layer (FGL) to decrease, resulting in a lack of spin torque efficiency.